The present invention generally relates to production/purchase management processing systems and methods, and more particularly to production/purchase management processing system and method which integrate the so-called material requirement planning (MRP) system and the project order system.
The project order system is a system which makes the arrangements for parts and intermediate products forming the final products for each final product which is to be delivered to the customer. The product number is assigned to each final product, and the purchase, assembling plan for the daily routine, the progress management, the cost accounting and the like are made in units of product numbers. Hence, even when there are parts and intermediate products which are common to the different final products, the planning and management thereof are made independently.
When managing production of products, different management systems are required depending on the characteristics of the products. In other words, some products are planned and mass produced, while other products are produced in small numbers on receipt of an order.
The MRP system is known as a system for managing planned mass production of products. According to the MRP system, the needs are consolidated depending on the item and period for each required item of a plurality of products. Hence, when there is a production order for an item, it is unclear to which product the item of the production order belongs. In addition, the MRP system is unsuited for managing the progress of the production and the cost for each final product (ordered item). For these reasons, the MRP system is unsuited for application to products which are produced in small numbers on receipt of an order.
On the other hand, the project order system is suited for application to products which are produced on receipt of an order because the parts of the final product as well as the final product are assigned the same number with strings. "With strings" means that the purchase orders of the parts, the assembling orders for the intermediate products and the assembling orders for the final products are correlated in units of the final product according to the project order system. However, it is difficult to cope with surplus parts and short delivery time limit.
FIGS. 1A, 1B and 1C are diagrams for explaining the concept of the MRP system.
FIG. 1A shows that a final product A is formed from parts B and P, and the part B is formed from parts C, . . . . In addition, a final product X is formed from parts B, . . . . Furthermore, a final product Y is formed from parts Q, . . . , and the part Q is formed from parts B, . . . .
In this case, the part B is required in a second level of the product A, the second level of the product X and the third level of the product Y. When obtaining the products A, X and Y with delivery time limits which are approximately the same, a schedule is made as shown in FIG. 1B for the part B when the MRP system is employed and the production order is made so that the schedule can be kept. In FIG. 1B, the number of the products A required is 30 for the first week, 40 for the second week and 50 for the third week. The number of the products X required is 10 for the first week, 50 for the second week and 15 for the third week. The schedule for the product Y and the parts P and Q is omitted for the sake of convenience. According to the schedules shown in FIG. 1B, the number of the parts B required is 120 for the first week, 200 for the second week and 300 for the third week.
FIG. 1C shows a schedule B(A) for the parts B required by the product A, a schedule B(X) for the parts B required by the product X and a schedule B(Y) for the parts B required by the product Y, for the first, second and third weeks. The schedules for the products A, X, . . . shown in FIG. 1B are called a master production schedule, and the master production schedule is formed based on the hierarchical structure of the products A, X and Y and the schedules shown in FIG. 1C. However, in the master production schedule, there is no information related to how many of the parts B, for example, are required by the products A, X and Y. In other words, there is no corresponding information to link each part and each product.
A modification of the MRP system has been proposed to indicate to which product each part belongs with strings. However, if the correspondence of each part and the product is indicated, an extremely long processing time is required to indicate the correspondence of the part and product and an extremely large filing space is required to store information related to the correspondence.
FIG. 2 is a diagram for explaining the processing of the MRP system. FIG. 2 shows a production planning processor 1 which carries out a production planning process for each item, a master production schedule 2 which is made up of the schedules for the products A, X and Y, a product construction/item master 3 for storing information related to items which are required when obtaining each product, stock/remaining order information 4 for supplying information related to the present stock (or stock quantity) and the remaining orders for each item, a purchase planning order 5 for satisfying a required number of an arbitrary item by purchase, and a production planning order 6 for satisfying a required number of an arbitrary item by production.
The item refers to the product or the part which forms the product.
In the case shown in FIGS. 1A through 1C, the production planning order 6 for the part B is output as 120 for the first week, 200 for the second week and 300 for the third week.
But as described above, the information shown in FIG. 1C does not exist in the production planning order 6 when the MRP system is employed. For this reason, there is a problem in that the MRP system is unsuited for producing the products on receipt of an order.